The invention relates to an electromagnetically operated valve construction, wherein a single magnetic circuit places plural valve members of magnetic material in series magnetically interlinked relation, for plural valves that are in series relation on a single line of fluid flow, such that a single electrical excitation coupled to the single magnetic circuit can simultaneously operate the plural valves, for redundant assurance of at least a shut-off condition in the single line of fluid flow.
U.S. Pat. Nos. 3,443,585, 3,472,277 and 4,223,698 disclose various magnetically actuated valve systems wherein a single electromagnetic excitation will actuate each of two valve members, each of which serves its own pressure-fluid flow. In U.S. Pat. No. 3,443,585, a permanent magnet is the common middle leg of two separate solenoid-actuated magnetic circuits. Excitation of one solenoid opens both valves; excitation of the other solenoid closes both valves, and the permanent magnet holds the actuated condition of both valves. U.S. Pat. Nos. 3,472,277 and 4,223,698 each disclose an electromagnetic actuating system wherein a single solenoid coil actuates two magnetically linked valves to open condition, against the compliant action of springs to load valve members in the valve-closing direction. In all cases, construction is highly specialized and complex, leading to unduly expensive products.
Pending U.S. patent application Ser. No. 08/194,722, filed in February 1994 discloses a simpler construction for the case of a single solenoid coil to actuate two magnetically linked valves to open condition in each of two lines of fluid flow, but there is a need for the safety assurance of a single solenoid coil to actuate two or more magnetically linked valves that are in series relation on the same single line of fluid flow, as when a particular line of rocket-fuel supply must be positively and rapidly shut down.